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|LETTER TO EDITOR
|Year : 2017 | Volume
| Issue : 5 | Page : 1176-1177
Rosette-forming glioneuronal tumor of the fourth ventricle
Rajashree Pradhan, Sajeeb Mondal, Subrata Pal, Sharmistha Chatterjee, Arindam Banerjee, Debosmita Bhattacharyya
Department of Pathology, College of Medicine and Sagore Dutta Hospital, North 24 Pargana, West Bengal, India
|Date of Web Publication||6-Sep-2017|
Kalpataru Apartment, Sahid Colony, BT Road, PS- Khardaha, North 24 Pargana, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pradhan R, Mondal S, Pal S, Chatterjee S, Banerjee A, Bhattacharyya D. Rosette-forming glioneuronal tumor of the fourth ventricle. Neurol India 2017;65:1176-7
Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle (World Health Organization grade I) is a rare slow-growing tumor occurring at a young age. This mixed tumor presents as distinctive neurocytic rosettes or perivascular pseudorosettes as well as with astrocytic components., RGNT has been predominantly diagnosed within the fourth ventricle and may extend to the surrounding structures, including the cerebellar vermis, cerebellopontine angle, and midbrain.,, Till date, a few cases have been documented in the world literature. We present a rare case of RGNT of the fourth ventricle in a young male patient.
A 21-year old male patient presented with headache for 2 months and gait disorder for the last 10 days. Noncontrast computed tomography (CT) scan revealed a mass involving the cerebellar vermis [Figure 1]. Magnetic resonance imaging (MRI) of the brain (T2 weighted) showed a discrete area of increased signal intensity without contrast enhancement. The provisional diagnosis was an astrocytoma.
|Figure 1: CT scan of the brain showing a large heterogenous posterior fossa tumor|
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He was treated with a midline suboccipital craniotomy and resection of the tumor mass. Histopathology of the tumor mass revealed two components. The glial component was composed of diffusely arranged neoplastic astrocytes with microcysts and myxoid areas [Figure 2]. The astrocytic tumor cells were spindle-to-stellate with elongated-to-oval nuclei having bipolar cytoplasmic extension forming a fibrillary background. The neurocytic component was composed of uniform neurocytes arranged in a rosettoid pattern surrounding a fibrillary material called neuropil [Figure 2]b. Mitosis and necrosis were absent in the sections. The final diagnosis was established as RGNT. The follow-up at 2 years did not reveal any significant neurological deficit and tumor recurrence.
|Figure 2: Photomicrograph showing histology of the rosette-forming glioneural tumor with different parts: (a) microcysts of the glial component; (b) rosettes in the neurocytic component; (c) the neurocytic components; and, (d) spindle-to-stellate neoplastic astrocytes in the glial component. [H and E stain, 40 × view]|
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RGNT was first described by Kuchelmeister et al., as a dysembryoplastic neuroepithelial tumor (DNET) of the cerebellum. It was largely recognized as RGNT in 2002 by Komori et al., During the last one decade, individual cases have been reported from different countries [Table 1]. These tumors mostly affect female patients (1.9:1) of a younger age group (mean age 30 ± 12.8 years)., The common sites of involvement are within the fourth ventricle and the posterior third ventricular region extending to the cerebellar vermis and midbrain.,, The common clinical presentations are headache, ataxia, vertigo, and vomiting. This tumor has an extremely indolent growth. Typical radiological findings (seen on T2 MRI images) of the tumor are an increased signal intensity and no contrast enhancement. Calcification and satellite lesions are sometimes noted.
The histology of RGNT includes a biphasic morphology of a neurocytic component and an astrocytic component. The neurocytic component shows rosettes (such as Homer–Wright rosettes) formed by neurocytes containing an eosinophilic core (synaptophysin positive) as well as perivascular pseudorosettes., The astrocytic component closely resembles a pilocystic astrocytoma. Microcysts, myxoid areas, and oligodendroglia-like cells may be seen. Rosenthal fibers are found in 60% of the cases.,, Necrosis and mitosis are absent in the tumor. In our case, the tumor had both the components along with microcysts, myxoid areas, and Rosenthal fibers. The histological differential diagnoses of RGNT include a pilocystic astrocytoma, dysembryoplastic neuroepithelial tumor, oligodendroglioma, and neurocytoma.,, On immunohistochemistry, RGNTs show a positive staining with synaptophysin at the core of the rosettes. Glial fibrillary acid protein and S-100 are variably positive in the glial component but are absent in the neurocytic component. Its proliferative index, assessed by KI-67 labelling, is usually low (0–3.8%). Complete resection of the tumor mass is an effective treatment. The resection of the tumor is associated with an excellent prognosis with little postoperative morbidity.
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[Figure 1], [Figure 2]